MIT Maps CO2-Injected Cement Chemistry, Showing 13% Higher 24-Hour Strength
Updated
Updated · MIT News · Jun 11
MIT Maps CO2-Injected Cement Chemistry, Showing 13% Higher 24-Hour Strength
3 articles · Updated · MIT News · Jun 11
Summary
MIT researchers used Raman confocal microscopy to directly watch CO2-injected cement harden over 24 hours, capturing the fast chemical sequence that had previously been inferred only indirectly.
Within the first hour, injected CO2 tied up calcium as calcium carbonate, then a silica-gel network spread through the paste; by four to eight hours, that gel reacted into widely distributed calcium silicate hydrate, the binder that boosts strength.
At 1% CO2 by cement weight, the paste delivered average compressive strength 13% higher at 24 hours than reference mixes because the new binder formed more uniformly across the matrix.
The study also challenges a leading theory: calcium carbonate crystals appear to be passive bystanders rather than seeds for binder growth, giving researchers a clearer target for tuning CO2 dosage.
That mechanism could help optimize commercial CO2-injected concrete and, in theory, offset up to 40% of cement-production emissions from the paste itself, though practical reductions would be smaller.
This discovery rewires cement with CO2, but could adding too much carbon dioxide actually make our future buildings weaker?
CO2 injection versus new cement formulas: which green concrete technology will ultimately win the race to rebuild our world?
Visualizing CO₂ in Cement: MIT’s Breakthrough and the Race to Decarbonize a 1.5 Billion Ton Industry
Overview
MIT's Concrete Sustainability Hub has achieved a major breakthrough by revealing how carbon dioxide interacts with cement at the earliest stages. Their new research details the chemical sequence that occurs when CO₂ meets fresh cement paste, showing that mineralization not only stores carbon but also changes the binder’s microstructure from the start. This insight helps the industry better understand carbon mineralization, allowing for the development of more sustainable and efficient construction materials. Industry leaders see this as a turning point, as it opens the door to creating high-quality, environmentally friendly cement products that meet demanding standards.